diff --git a/docs/cli/update.md b/docs/cli/update.md
index 2b7a77fd6364..ad80ba6f6cbf 100644
--- a/docs/cli/update.md
+++ b/docs/cli/update.md
@@ -251,7 +251,7 @@ returns the latest sentinel.
     Dev only.
   </Step>
   <Step title="Preflight build (dev only)">
-    Runs the TypeScript build in a temp worktree. If the tip fails, walks back up to 10 commits to find the newest buildable commit. Set `OPENCLAW_UPDATE_PREFLIGHT_LINT=1` to also run lint during this preflight; lint runs in constrained serial mode because user update hosts are often smaller than CI runners.
+    Runs the TypeScript build in a temp worktree. If the tip fails, walks back up to 10 commits to find the newest buildable commit. Content-addressed declaration outputs from the successful candidate are reused by the final checkout build; rebased source changes automatically invalidate the affected cache groups. Set `OPENCLAW_UPDATE_PREFLIGHT_LINT=1` to also run lint during this preflight; lint runs in constrained serial mode because user update hosts are often smaller than CI runners.
   </Step>
   <Step title="Rebase">
     Rebases onto the selected commit (dev only).
@@ -259,8 +259,8 @@ returns the latest sentinel.
   <Step title="Install dependencies">
     Uses the repo package manager. For pnpm checkouts, the updater bootstraps `pnpm` on demand (via `corepack` first, then a temporary `npm install pnpm@11` fallback) instead of running `npm run build` inside a pnpm workspace. If pnpm bootstrap still fails, the updater stops early with a package-manager-specific error instead of trying `npm run build` in the checkout.
   </Step>
-  <Step title="Build Control UI">
-    Builds the gateway and the Control UI.
+  <Step title="Build checkout">
+    Builds the gateway and Control UI once in the final checkout. The updater runs the standalone Control UI build only when a target build omitted those assets or doctor later removes them.
   </Step>
   <Step title="Run doctor">
     `openclaw doctor` runs as the final safe-update check.
diff --git a/scripts/build-all.mjs b/scripts/build-all.mjs
index 830b7088c4ec..906aa05282c3 100644
--- a/scripts/build-all.mjs
+++ b/scripts/build-all.mjs
@@ -635,9 +635,21 @@ function normalizePortablePath(filePath) {
   return filePath.replaceAll("\\", "/");
 }
 
-function resolveCachePaths(rootDir, step) {
+function resolveBuildCacheRoot(rootDir, env) {
+  // Dev update preflight and final builds run in separate worktrees. A shared
+  // root lets content signatures decide reuse without relocating built trees.
+  const configuredRoot = env?.BUILD_ALL_CACHE_ROOT?.trim();
+  if (!configuredRoot) {
+    return path.resolve(rootDir, ".artifacts/build-all-cache");
+  }
+  return path.isAbsolute(configuredRoot)
+    ? path.normalize(configuredRoot)
+    : path.resolve(rootDir, configuredRoot);
+}
+
+function resolveCachePaths(rootDir, step, env) {
   const safeLabel = step.label.replace(/[^a-zA-Z0-9._-]+/g, "_");
-  const cacheDir = path.resolve(rootDir, ".artifacts/build-all-cache", safeLabel);
+  const cacheDir = path.join(resolveBuildCacheRoot(rootDir, env), safeLabel);
   return {
     cacheDir,
     outputRoot: path.join(cacheDir, "outputs"),
@@ -703,7 +715,7 @@ export function resolveBuildAllStepCacheState(step, params = {}) {
     step.cache.env ?? [],
     params.env ?? process.env,
   );
-  const { outputRoot, stampPath } = resolveCachePaths(rootDir, step);
+  const { outputRoot, stampPath } = resolveCachePaths(rootDir, step, params.env ?? process.env);
   const stamp = readCacheStamp(stampPath, fsImpl);
   const outputFiles = listCacheFiles(rootDir, step.cache.outputs, fsImpl);
   const relativeOutputFiles = outputFiles.map((file) => portableRelativePath(rootDir, file));
diff --git a/src/infra/update-runner-git-commands.ts b/src/infra/update-runner-git-commands.ts
index f59efff7ae28..c3cb9d3df98a 100644
--- a/src/infra/update-runner-git-commands.ts
+++ b/src/infra/update-runner-git-commands.ts
@@ -42,13 +42,20 @@ function resolveBuildNodeOptions(baseOptions: string | undefined): string {
   return current.replace(/(?:^|\s)--max-old-space-size=\d+(?=\s|$)/, ` ${desired}`).trim();
 }
 
-export function resolveBuildEnv(env?: NodeJS.ProcessEnv): NodeJS.ProcessEnv | undefined {
+export function resolveBuildEnv(
+  env?: NodeJS.ProcessEnv,
+  buildCacheRoot?: string,
+): NodeJS.ProcessEnv | undefined {
   const currentNodeOptions = env?.NODE_OPTIONS ?? process.env.NODE_OPTIONS;
   const nextNodeOptions = resolveBuildNodeOptions(currentNodeOptions);
-  if (nextNodeOptions === currentNodeOptions) {
+  if (nextNodeOptions === currentNodeOptions && !buildCacheRoot) {
     return env;
   }
-  return { ...env, NODE_OPTIONS: nextNodeOptions };
+  return {
+    ...env,
+    NODE_OPTIONS: nextNodeOptions,
+    ...(buildCacheRoot ? { BUILD_ALL_CACHE_ROOT: buildCacheRoot } : {}),
+  };
 }
 
 export function resolveInstallEnv(
diff --git a/src/infra/update-runner-git-preflight.ts b/src/infra/update-runner-git-preflight.ts
index 73fa7123c9f5..2dda39ed6af7 100644
--- a/src/infra/update-runner-git-preflight.ts
+++ b/src/infra/update-runner-git-preflight.ts
@@ -392,7 +392,7 @@ async function testPreflightCandidates(params: {
           `preflight build (${shortSha})`,
           managerScriptArgs(manager.manager, "build"),
           params.worktreeDir,
-          resolveBuildEnv(manager.env),
+          resolveBuildEnv(manager.env, path.join(params.gitRoot, ".artifacts", "build-all-cache")),
         ),
       );
       params.steps.push(buildStep);
diff --git a/src/infra/update-runner-git.ts b/src/infra/update-runner-git.ts
index 4348ab75ea39..f636dfef18be 100644
--- a/src/infra/update-runner-git.ts
+++ b/src/infra/update-runner-git.ts
@@ -70,7 +70,7 @@ export async function runGitUpdate(params: {
   const branch = await readBranchName(runCommand, gitRoot, timeoutMs);
   const hasDevTargetRef = channel === "dev" && Boolean(opts.devTargetRef?.trim());
   const needsCheckoutMain = channel === "dev" && !hasDevTargetRef && branch !== DEV_BRANCH;
-  const totalSteps = channel === "dev" ? (needsCheckoutMain ? 12 : 11) : 10;
+  const totalSteps = channel === "dev" ? (needsCheckoutMain ? 11 : 10) : 9;
   const steps: UpdateStepResult[] = [];
   let stepIndex = 0;
   const step = (
@@ -389,7 +389,10 @@ export async function runGitUpdate(params: {
         "build",
         managerScriptArgs(manager.manager, "build"),
         gitRoot,
-        resolveBuildEnv(manager.env),
+        resolveBuildEnv(
+          manager.env,
+          channel === "dev" ? path.join(gitRoot, ".artifacts", "build-all-cache") : undefined,
+        ),
       ),
     );
     steps.push(buildStep);
@@ -410,12 +413,20 @@ export async function runGitUpdate(params: {
     if (buildCleanCheck.stdoutTail?.trim()) {
       return await rollbackError("build-dirty");
     }
-    const uiBuildStep = await runStep(
-      step("ui:build", managerScriptArgs(manager.manager, "ui:build"), gitRoot, manager.env),
-    );
-    steps.push(uiBuildStep);
-    if (uiBuildStep.exitCode !== 0) {
-      return await rollbackError("ui-build-failed");
+    const builtUiIndexHealth = await resolveControlUiDistIndexHealth({ root: gitRoot });
+    if (!builtUiIndexHealth.exists) {
+      const uiBuildStep = await runStep(
+        step(
+          "ui:build (build fallback)",
+          managerScriptArgs(manager.manager, "ui:build"),
+          gitRoot,
+          manager.env,
+        ),
+      );
+      steps.push(uiBuildStep);
+      if (uiBuildStep.exitCode !== 0) {
+        return await rollbackError("ui-build-failed");
+      }
     }
 
     const doctorEntry = path.join(gitRoot, "openclaw.mjs");
diff --git a/src/infra/update-runner.test.ts b/src/infra/update-runner.test.ts
index d68bc6f1ee66..ff735c603c46 100644
--- a/src/infra/update-runner.test.ts
+++ b/src/infra/update-runner.test.ts
@@ -1849,7 +1849,7 @@ describe("runGatewayUpdate", () => {
     expect(calls).toContain("pnpm install");
     expect(calls).toContain("pnpm build");
     expect(calls).not.toContain("pnpm lint");
-    expect(calls).toContain("pnpm ui:build");
+    expect(calls).not.toContain("pnpm ui:build");
     expect(pnpmEnvPaths.filter((envPath) => envPath.includes("openclaw-update-pnpm-"))).not.toEqual(
       [],
     );
@@ -2262,10 +2262,11 @@ describe("runGatewayUpdate", () => {
     expect(cleanupStep?.stderrTail ?? "").toContain("fallback cleanup removed preflight tree");
   });
 
-  it("adds heap headroom to pnpm build steps during dev updates", async () => {
+  it("shares the build cache while adding heap headroom to dev builds", async () => {
     await setupGitPackageManagerFixture();
     const upstreamSha = "upstream123";
     const buildNodeOptions: string[] = [];
+    const buildCacheRoots: string[] = [];
     const doctorNodePath = await resolveStableNodePath(process.execPath);
     const doctorCommand = `${doctorNodePath} ${path.join(tempDir, "openclaw.mjs")} doctor --non-interactive --fix`;
 
@@ -2327,6 +2328,7 @@ describe("runGatewayUpdate", () => {
       }
       if (key === "pnpm build") {
         buildNodeOptions.push(options?.env?.NODE_OPTIONS ?? "");
+        buildCacheRoots.push(options?.env?.BUILD_ALL_CACHE_ROOT ?? "");
         return { stdout: "", stderr: "", code: 0 };
       }
       if (
@@ -2352,6 +2354,10 @@ describe("runGatewayUpdate", () => {
     expect(result.status).toBe("ok");
     expect(buildNodeOptions).toHaveLength(2);
     expect(buildNodeOptions).toEqual(["--max-old-space-size=8192", "--max-old-space-size=8192"]);
+    expect(buildCacheRoots).toEqual([
+      path.join(tempDir, ".artifacts", "build-all-cache"),
+      path.join(tempDir, ".artifacts", "build-all-cache"),
+    ]);
   });
   it("pins dev updates to an explicit target ref when requested", async () => {
     await setupGitPackageManagerFixture();
@@ -3314,11 +3320,31 @@ describe("runGatewayUpdate", () => {
     const result = await runWithCommand(runCommand, { channel: "stable" });
 
     expect(result.status).toBe("ok");
-    expect(getUiBuildCount()).toBe(2);
+    expect(getUiBuildCount()).toBe(1);
     expect(await pathExists(uiIndexPath)).toBe(true);
     expect(calls).toContain(doctorKey);
   });
 
+  it("builds Control UI separately only when the checkout build omitted it", async () => {
+    await setupGitCheckout({ packageManager: "pnpm@8.0.0" });
+    const uiIndexPath = path.join(tempDir, "dist", "control-ui", "index.html");
+    const stableTag = "v1.0.1-1";
+    const { runCommand, calls, doctorKey, getUiBuildCount } = await createStableTagRunner({
+      stableTag,
+      uiIndexPath,
+      onUiBuild: async () => {
+        await fs.mkdir(path.dirname(uiIndexPath), { recursive: true });
+        await fs.writeFile(uiIndexPath, "<html>built</html>", "utf-8");
+      },
+    });
+
+    const result = await runWithCommand(runCommand, { channel: "stable" });
+
+    expect(result.status).toBe("ok");
+    expect(getUiBuildCount()).toBe(1);
+    expect(calls.indexOf("pnpm ui:build")).toBeLessThan(calls.indexOf(doctorKey));
+  });
+
   it("fails when UI assets are still missing after post-doctor repair", async () => {
     await setupGitCheckout({ packageManager: "pnpm@8.0.0" });
     const uiIndexPath = await setupUiIndex();
@@ -3327,12 +3353,6 @@ describe("runGatewayUpdate", () => {
     const { runCommand } = await createStableTagRunner({
       stableTag,
       uiIndexPath,
-      onUiBuild: async (count) => {
-        if (count === 1) {
-          await fs.mkdir(path.dirname(uiIndexPath), { recursive: true });
-          await fs.writeFile(uiIndexPath, "<html>built</html>", "utf-8");
-        }
-      },
       onDoctor: removeControlUiAssets,
     });
 
diff --git a/test/scripts/build-all.test.ts b/test/scripts/build-all.test.ts
index 99c355f5d401..bf207ef71835 100644
--- a/test/scripts/build-all.test.ts
+++ b/test/scripts/build-all.test.ts
@@ -736,6 +736,49 @@ describe("build-all timing output", () => {
 });
 
 describe("resolveBuildAllStepCacheState", () => {
+  it("shares content-addressed outputs across checkout roots", () => {
+    const cacheRoot = fs.mkdtempSync(path.join(os.tmpdir(), "openclaw-shared-build-cache-"));
+    const firstRoot = fs.mkdtempSync(path.join(os.tmpdir(), "openclaw-build-cache-source-"));
+    const secondRoot = fs.mkdtempSync(path.join(os.tmpdir(), "openclaw-build-cache-target-"));
+    const step = {
+      label: "cached",
+      cache: {
+        inputs: ["src"],
+        outputs: ["dist"],
+        restore: "always" as const,
+      },
+    };
+    const env = { BUILD_ALL_CACHE_ROOT: cacheRoot };
+
+    try {
+      for (const rootDir of [firstRoot, secondRoot]) {
+        fs.mkdirSync(path.join(rootDir, "src"), { recursive: true });
+        fs.writeFileSync(path.join(rootDir, "src/input.ts"), "same input");
+      }
+      fs.mkdirSync(path.join(firstRoot, "dist"), { recursive: true });
+      fs.writeFileSync(path.join(firstRoot, "dist/output.js"), "cached output");
+
+      const sourceState = resolveBuildAllStepCacheState(step, { rootDir: firstRoot, env });
+      writeBuildAllStepCacheStamp(
+        step,
+        resolveBuildAllStepCacheStampState(step, sourceState, { rootDir: firstRoot }),
+        { rootDir: firstRoot },
+      );
+
+      const targetState = resolveBuildAllStepCacheState(step, { rootDir: secondRoot, env });
+      expect(targetState).toMatchObject({ fresh: true, restorable: true });
+      expect(targetState.outputRoot).toBe(path.join(cacheRoot, "cached", "outputs"));
+      expect(restoreBuildAllStepCacheOutputs(targetState, { rootDir: secondRoot })).toBe(true);
+      expect(fs.readFileSync(path.join(secondRoot, "dist/output.js"), "utf8")).toBe(
+        "cached output",
+      );
+    } finally {
+      fs.rmSync(cacheRoot, { force: true, recursive: true });
+      fs.rmSync(firstRoot, { force: true, recursive: true });
+      fs.rmSync(secondRoot, { force: true, recursive: true });
+    }
+  });
+
   it("invalidates only declaration groups that depend on the changed module", () => {
     const rootDir = fs.mkdtempSync(path.join(os.tmpdir(), "openclaw-tsdown-group-cache-"));
     const ai = getBuildAllStep("tsdown-ai");